The present invention relates to computer networks, and more particularly, to a computer server that provides Internet access to computers configured for a different server without requiring reprogramming of the computers.
The present invention may be more easily understood with reference to a mobile computer user who utilizes a portable computer that is configured for the computer network at the user""s headquarters. When the user is connected to the headquarters"" network, the user has high speed access to the resources of that network which typically include file servers, internet access, and E-Mail. When the user unplugs her computer from this network and travels to a hotel, this high-speed access is typically lost.
The most common form of remote access is via a modem over a conventional phone line. Since the bandwidth of a conventional phone line is much lower than that of a typical office network, the time needed to complete any significant data transfer from the headquarters"" network can be substantial.
To make matters worse, most hotels utilize phone systems that are poorly adapted to high-speed digital transmissions. The phone systems were designed to accommodate voice transmissions having a relatively short duration compared to the duration of the average network connection. Hence, if a large number of hotel guests are making modem calls to connect to their corporate networks, the hotel phone system runs out of capacity to service the traffic. In addition, many digital PBX systems utilize signal levels that are incompatible with conventional computer modems, thus making even this type of low bandwidth connection impossible.
Accordingly, systems for providing high-speed network access within a hotel or similar facility have been suggested to cure these problems. Ideally, the mobile user would plug her computer into an Ethernet network at the hotel, which includes a server connected to the Internet. The user could then enjoy the same high-speed access that was available at her corporate headquarters. Furthermore, such a system would by-pass the telephone system within the hotel, thereby avoiding the capacity problems described above.
Unfortunately, the software that oversees the network connection typically includes addresses that are particular to the network. For networks connected to the Internet, each computer on the network is assigned an address of the form A.B.C.D where A, B, C, and D are 8-bit integers. One of these addresses corresponds to the network server that connects the local office network to the Internet. A computer wishing to communicate with another computer on the network, including the server, directs a message to that computer using its address. The server is programmed to recognize the addresses that are particular to the local area network. When the server sees a message for an address that is not part of the local area network, the server forwards the message to the Internet. Similarly, when the server detects an incoming message from the Internet with a destination address for one of the computers on the local area network, the server transfers that message to the local area network and the appropriate computer accepts the message.
Since the addresses on each local area network are unique, when a computer is moved from one local area network to another, the computer""s address will not be recognized by the server in the new network as being part of that server""s local area network. Furthermore, a message from the mobile computer to the server address it associates with the Internet will not be recognized by the current server as a request for sending a message to an address on the Internet. Hence, a new address must be assigned to the business traveler""s computer when she connects it to the hotel""s local area network.
One solution to providing the new address requires the user to enter an address provided by the hotel server when the traveler first logs onto the network. However, this solution to the problem requires two reconfigurations of the traveler""s computer, once when she logs onto the hotel network and once when she returns to her office network. Such reconfigurations require expertise that is outside the computer skills of the typical business traveler. In addition, the business traveler must keep a copy of her old network address so that she can reconfigure her computer on return to her own network. Another solution is to allow the traveler""s computer to dynamically receive an address from the server using a protocol such as DHCP or BOOTP. However, since many corporate networks do not use such protocols, travelers will still need to reconfigure their computers to enable DHCP or BOOTP. Such reconfigurations also result in business traveler losing track of her old network address.
A second problem with hotel local area networks arises from security concerns. A local area network that connects all of the guest rooms allows any guest to xe2x80x9cseexe2x80x9d the contents of the computers of another guest if the other guest""s computer has been programmed to allow file sharing. Such sharing may have been setup for use in the headquarters"" local area network environment. However, it clearly can pose security problems in the hotel setting. Since the business traveler""s computer may have been programmed by her company technicians, she may not know that such a security problem exists, no less have the technical expertise to turn off the file sharing option.
Broadly, it is the object of the present invention to provide an improved local area network for use in hotel-like environments.
It is a further object of the present invention to provide a local area network that does not require the user to reconfigure her computer address when she logs onto the network.
It is a still further object of the present invention to provide a local area network that protects individual computers from access by other computers on the network without requiring reconfiguration of the file sharing options on the computer.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.
The present invention is a method for operating a local area network having a server and a plurality of computers. The server includes an Internet gateway for directing messages to and from the Internet. Each computer in the network has a unique IP address and a unique network adapter address associated with that computer. Each computer determines the network adapter address associated with a target IP address by broadcasting an address resolution protocol (ARP) message on the local area network. The ARP includes the target IP address and the network adapter address and IP address of the computer broadcasting the ARP. The computer having the target IP address responds to an ARP by sending a response message that includes the network adapter address of the computer having the target IP address. In the present invention, the server stores information identifying IP addresses in a foreign class corresponding to computers not configured for connection to the local area network. The server responds to each ARP having a target IP address in the foreign class by returning the network adapter address of the server in the response message and assigning an IP address associated with the local area network to the IP address of the computer sending the ARP. The server translates each outbound message originating on the local area network for a destination address in the foreign class from an originating address for which one of the IP addresses associated with the local area network has been assigned. The translation consists of replacing the IP address of the computer originating the message with the corresponding IP address assigned to that computer. The translated message is then sent via the gateway. The sever also examines each inbound message received on the gateway for a destination IP address associated with the local area network to determine if the destination address is an IP address that has been assigned to an IP address in said foreign class. If such an assignment has been made, the server replaces the destination IP address in the message with the foreign IP address and sends the inbound message on the local area network.